Dynamically balanced weight system



June l2, 1951 F. w. LEE 2,556,199

' DYNAMICALLYBALANCED WEIGHT' SYSTEM Filed neo. s1, 1947 1 4 sheets-sheet 1 y 1HE-...1 /aa 619 J5 f .--l i 55a ,f/ a

ArroR/vy' June 12, .1951 F. w. LEE 2,556,199

DYNAMICALLY BALANCED WEIGHT SYSTEM Filed Dec. 31, 1947 4 Sheets-Sheet 2 :SIE- E.

907 55 ,C29 33 W Il' June 12, 1951 F. w. LEE 2,556,199

DYNAMICALLY BALANCED WEIGHT SYSTEM 31E-...E 1112-... .7 Y @1 l v Aron/vfy June 12, 1951 F. w. LEE 2,556,199

DYNAMICALLY BALANCED WEIGHT SYSTEM Filed Dec. 31, 1947 4 Sheets-Sheet 4 :Fa- 1i Patented June 12, 1951 Application December 31, 1947, serial Nc. '194,881v

9 claims. (o1. 175'1 ss) i My invention relates broadly to instruments for conducting magnetic surveys and more particularly to a sensitive instrument for measuring magnetic elds relating to ore bodies, geological bodies and structures, crystalline basements and other sources of magnetic anomalies. l

One of the objects of my invention is to provide a `construction of highly sensitive magnetic observing instruments for conducting magnetic Surveys Another object of my invention is to provide a y construction of magnetic measuring instrument, including means for mechanically counterbalancing both vertical and horizontal components of the eiects of the magnetic eld upon the meas.- uring instrument for accurately determining the magnetic field pattern of ore bodies, geological bodies or structures, crystalline basements, and other sources of magnetic anomalies.

Another object of my invention is to provide a construction of magnetic measuring instrument having an indicating magnetic needle operative over a calibrated scale and associated with composite adjustable magnetic and mechanical means for counterbalancing the indicating magnetic needle and predetermining the zero position thereof.

Other and further objects of my invention reside in a precision construction of magnetic measuring instrument as set forth more fully in the specication hereinafter following by reference to the accompanying drawngsin which:

Figure 1 is a front elevational view of the magnetic measuring instrument of my invention;

Fig. 2 is an enlarged front elevational View of the counterbalancing mechanism for the magnetic indicating needle and illustrating certain of the parts in vertical section for more clearly disclosing the coaction of the parts of the measuring instrument; Fig. 3 is a vertical sectional view taken substantially on line 3--3 of Fig. 2; Fig. 4 is a horizontal sectional view taken through one of the magnetic compensating means associated the compass which issupported by the depending pendulum; Fig. 10 is a fragmentary side elevation and vertical sectional view of a portion of the pendantly-supported pendulum and illustrating the magnetic compensating 'means mounted therein; Fig. 11 is a view of the portion of thependantly mounted pendulum illustrated in Fig.

10 but viewed from a 90 degree position beyondv the position illustrated in Fig. 10; Fig. 12 is a horizontal sectional view taken substantially on line |2-I2 of Fig. 11 Fig..13 is a horizontalview taken substantially on`linefl3-I3 of Fig. 11; and Figs. 14-16 are theoretical views explaining the operation of my invention.

The subject matter of this invention concerns an instrument for measuring magnetic elds and in particular those magnetic elds related to ore bodies, geological bodies and structures, crystalline basements and other sources of magnetic with the measuring instrument of my invention;

Fig. 5 is a vertical sectional view of one of the magnetic compensating means of my invention; Fig. 6 is an end View of the magnetic `compensating means illustrated in Fig. 4 looking in the direction of arrow A in Fig. 4; Fig. 7 is a vertical sectional view through the magnetic'compensating means taken on line 'i-'l of Fig. 4; Fig. 8 is a horizontal sectional view showing the pendulumsupported compass and taken approximately on line V8 8 of Fig. 1; Fig. 9 is a horizontal sectional view taken on line 9-9 of Fig. 1 and illlllraitrlg' anomalies. vThe instrument is new in that thesame measuring arrangement combined in one instrument rwill measure the following for which a separate instrument is usually employed:

a. The vertical component of the magnetic eld.

b. The variation of the vertical the magnetic eld.

component of A c. The horizontal component of the magnetic field. f

d. The variation of the horizontal component' ofthe magnetic field. l

e. The declination and the inclination of the magnetic field.

There are a large -number of newand novel` features embodied in my invention for 'materially' cutting down the costs for makingmagnetic sur- Veys.

Referring to the drawings in detail, reference Y character l designates the magnetic indicating4 needle of the measuring instrument of -my invention, the needle being journaled upon a horizontal axis 2 for swinging movementwith respect to the calibrated scale 3. The needle l has an indisupported by, and journaled in a U -shaped frame 4 to which is also attached the scale 3. A gimbal kcating arm la connected thereto for registering with the calibrations on scale 3. The needle I ismounting formed by -a multiplicity of coacting ring members is provided for supporting the.

vhousing 4a with which the U--shaped frame `Il is associated. The gimbal mechanism is represented by vcross rod 5 secured to ring 6 which is in turn journaled by means of diametrically eX- `tending rod members 1 in upstanding lugs- 151 which are attachedl tothe vrotatable unit `ll carrying the degree scale Ila at its periphery. The rotatable unit I1 is apertured through its center and is represented at I'Ib, the aperture being several times larger than the diameter of the stem 8 of the depending pendulum, whereby, the stem 8 of the pendulum can swing freely when the measuring instrument is properly mounted on the tripod support 20. The tripod support 20 serves as a mounting means for the stationary unit I8 which. is. also calibrated. to permit, the; recording of the azimuthfal position of the rotatable unit I I by the quadrant mark I9 on stationary unit I8. The stationary unit I8 is provided. with depending lugs I 8a for attachment of the legs of the tripod support 2U. Stationary uni-t I 8 also is equipped with a clamping screw lb for holding the unit I8 in selected'position. The stationary unit I 8 also providesmounting meansV for the circular guide ring I8c which is sus.-` pended through arms IBd extending from the lugs I8a.

The stern 8 of the pendulum is: composed of a non-metallic hollow tube within which the adjustable rod-like magnet 8c is' arranged. The magnet 8a may be clamped in any selected position in the pendulum by means or clamping screw 9 acting upon the clamping member I8 on oppOsitey sides of the longitudinally' extending slot 8b in the stem 8:. The clamping member I0, serves as an indexing member for locating the magnet' 8a in a selected position within the pendulu-rn with reference to the calibrations 8c on the stem 8. The rod-like magnet 8amay thus move upwardly or downwardly alongV the stem 8 for eiiecting desired magneteounterbalancing ofthe magnet indicating needle Iof the instrument. The lower portion off the stem 81s provided with a wide slot or recess 8d therein, throughwhich the rod-like magnet 8a' may be introduced into the stern 8er removed therefrom for effecting the desired compensation.

The compass I2 having compass needle I3' is mounted-at the bottom of thestern 8 together with a counterweight I4. A set screw Si enables the compass I2 to be adjusted in an angular position with respect to the stem 8. The counter- Weight I4 has a rod-like member 58; extending diametrically therethrough. The rod-like member- 58 is screw-threaded' on opposite ends to receive the adjustable weights 59 and 60 which may be rotatedl on the rod-like member 8 to shi-ft the weights toward or away froml the central axis of the stem 8. The compass I 2 is also equipped with a level or plumb indicator represented at I2a. The compress is suliiciently removed from the magnetic indicating needle I so as not to interfere with each other.

With the parts of the measuringv instrument accurately machined and finished to verysmall tolerances, the axis 2 of the magnetic indicating needle I may take a levell position when the pendulum, constituted` by stem 8, and depending compass I2, andcounterweights I4, 5'9, and 68 4 3. Also by rotating rotatable unit II by 90 degrees the direction of the needle I will be in the horizontal direction of the magnetic field. There is also provided for properly placing the level line in its correct relation to the scale the balance adjustment composed of the parts 58, 59 and 60. Adjustment of the weights 5S and 68 and adjustment of set screw 6I permits movement of the compass about stem 8 into the azimuth which will permitA they lineL of, vertical; adjustment to follow into properrelation.

The pivot at the axis 2 is mounted for operation with minimum friction by use or" jewel or ball bearings 2l and 22 set into adjustable screw members 23 and 24Y threaded into the main U- shaped frame. 4. There is a special advantage in using ball bearings 2l and 22 because such bearingscan support: a relatively heavy magnetic indicating needle I with compensating adjustments connected therewith. By making the U-shaped frame 4 of one solid piece, the perfect alignment of the screw holesl for the bears 23, and 24 is, possibie since both can be` drilled and tapped at one time and laid off from squared surfaces. There is alsoA provided a trough 26' into which the pole ends of the indicating needle rotate.

This trough is made of copper and dampens the swing of the indicating needle'.- The trough may extend' circumferentialy of; the calibrated scale 3 .and the graduations of the scale 3' may extend over the surface of the trough.

The housingV 4a which encloses theA U-shaped frame 4 provides diametrically opposite supports 29 for tubular housings which enclose compeneatingy magnets; The diametrically opposite sup- 'ports' 29l` are secured through magnetic seemingV means 29dI with the housing 4a in diametrical'ly opposite alignment so that indicatingV needle I may register diametrically therewith. The supports 29 are each internally screw-threaded at 29h' andv receive the screw-threaded ends of tubular members or housings 33 which abut with.

39 and 40, carried by tubular members 33. The

position of the rod members 32 and 34 control the horizontal magnetic component through the magnetic indicating needle I.

Thehousing 4a is closed at each side yby means of plate glass members 62 and 63 secured in position by means ofy removable wire-like springs 62a and 63a. A sighting slit 3I is placed in frame support 4a to permit the orientation of azimuths of the needle with reference to base lines astronomically determined. This arrangement, together with the azimuthal scale 3, Fig. l, permits the measurement of the magnetic declination of the earths field. It also serves to mark the direction of successive stations of measurement along a traverse line by sighting back and ahead through the slits for a iixed azimuthal direction. There isa very distinct advantage by combining this slit with the selfleveling arrangement which always places this slit 3|4 automatically in a vertical position.

By starting the graduations with the zero value on the level line, it is possible to make the Scale divisions of such a character as will permit system composed of rod members 32, and 34, ad`

justably mounted in tubular members 33. Tubular members 33 form extensions which can be screwed into supports 29, both having the same mass symmetrically placed about the median line running through the center of suspension 33 and the center of gravityof the movable pendulum, so as not to disturb the level position of the level line 31 with reference to the scale 3. The two identical adjustable rod members 32 and 34 of the same length, each having the same calibrated scale 32a and 34a, slide into tubular members 33 and can be clamped into selected time.

positions by'set screws 39 and 40. The magnetic l rods 32--34 act as a horizontal in line magnetic counterpoise to the horizontal magnetic field and is useful in this magnetometer for measuring the variation of the horizontal component of the magnetic field. In order to keep the system bal- 33 in reversed direction for magnetically con- Y- trolling the operation of the instrument.

The operation of this instrument in relation to the automatic level line 31 is described in connection with Figs. 14-15-16. In Fig. 14 we show two counterpoise 42 and 43 for adjusting the sensitivity or center of mass in a vertical direction. Two additional counterpoise, 54 and 55, serve to adjust the center of mass in a horizontal direction of the needle I as shown in Fig. 14. For making observation for determining the total absolute value of the magnetic fields both vertical and horizontal components, it is essential that the center of mass be directly below the center of suspension -PP (2) in relation to the level line 31 and the calibration of the functional scale 3. This instrument provides both an automatic level line directly concerned with the measurement function and also a functional scale directly related thereto. When the needle I swings in the east-west plane, as shown in Fig. 15,and is therefore not able to move because of the turning effort of the horizontal magnetic component, the instrument measures only the vertical component Hz of magnetic eld or variations of the vertical component aHZ. Under this arrangement, when the needle comes to rest in an equilibrium position making an angle a with the level line 31, the magnetic couple and the gravity restoring torque are equal and the following relations apply:

Gravity Torque=Magnetic Torque Mg. a sin a=llzmb cos a Here M is the mass of the rotating element a is the distance of center of mass from center of axis of rotation, g is the gravity constant, m is the pole strength of the magnet' I, b is the disy 6 I and a is the angle of deection. The means 42 and 43 are provided for adjusting the center of mass o n a line perpendicular to the needle and also passing through axis of rotation of the needle I. See Figs. 3 and 14.

Under this special condition it follows directly that Mga sin a Hz 75E-cos a Eq (l) Once the needle is properly adjusted by above means C is constant and the function is tan a which is proportional to HZ and hence the scale 3 of Fig. 2 is the tangent scale measured from the zero level line automatically provided for in this instrument.

For measuring the horizontal component Hxy consider the moment relations in Figure 16. Under this condition the plane of the swing of needle is in the north-south magnetic plane by =C tan a means provided by the compass needle I3. Here both the vertical component Hz as well as the horizontal component Hxy are acting at the same The following relations hold only for automatic level reference line 31, and means are provided therefore as previously described.

Under this north-south plane of swing of the i needle I of the magnetic moment of vertical component plus magnetic moment of horizontal component is equal to the restoring gravity moment.

sin a Eq. (3)

It will be noted that the term C tan a' has the same form as the value for the vertical com1 ponent, Eq. l which here may be called a hypothetical or assumed vertical component called for convenience Hz. This value is read directly from the scale 3 of Fig. 2. Equation (5) now becomes The cotangent of a is registered directly on the scale of the reverse side, such as scale 3a in Fig. 2. The total magnetic field HT is the vector sum of Hz and Hey Eq. (8)

Hif=vm and the angle of inclination 0=tan1ltlju Eq. (9)

netic units generally measured in gammas per scale deflection. The value of a. is controlled by the sensitivity adjustment screws 42 and 43. Figs. 2 and 3. When u. is small its sensitivity is high, when large its sensitivity is low. The limit o f sensitivity is in the bearing support 2.

abmfiac In addition to the precision balancing of the magnetic indicating needle in the measuring incombines both` measurement correction and orientation correction in one unit and does not require separate corrections for vertical components and horizontal components.

Automatic leveling is secured, which was not possible in earlier instruments which required f leveling by thumb screws. y

Magnetic intensities may be read directly on the scales of the instrument by reason of calibrations according to the special scale functions which require no subsequent mathematical interpolations.

While I have found the instrument of my invention highly practical in its construction and operation I realize that modifications Aand changes may be made and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

`What I claim as new and desire to secure by Letters Patent of the United States is as follows:

l. A magnetometer comprising a circular frame structure, a circular magnet having a gap therein and housed within said frame structure, a U-.shaped member terminating in a pair of substantially parallel faces extending between the ends of said circular magnet at the gap therein, an armature member jcurnalled between said pole faces, said armature member including pairs of diametrically extending projections each having screw-threaded ends, counterbalance weights adjustably screw-threaded on the screwthreaded ends of said armature member, an indicator secured in one of said projections and permanent magnets extending in opposite directions from a pair of projections on said armature member.

2. A magnetometer comprising a circular frame structure, a circular magnet having a gap therein with spaced end portions mounted within said circular frame structure, a U-shaped member mounted in said frame structure between the spaced ends of said circular magnet at the gap therein, an armature journalled in saidv U-shaped weights engaging said screw-threads, and an indicatcr secured to one of said arms and permanent magnets secured in others of said arms.

3. A magnetometer comprising a circular frame structure, a circular magnet having a gap therein, a calibrated scale, means supporting said circular magnet and said scale within said frame structure, said circular magnet having its ends terminating in aligned spaced relation at the gap therein, a U-shaped frame mounted between the spaced ends of said magnet, an armature journalled in said U-shaped frame centrally of said circular frame structure, said armature having sets of arms extending in diametrically opposite directions normal to each other,

an indicator 'carriedfby one of said arms andy coacting with said scale and permanent magnets carried by others of said arms and coacting with the circular magnet within said frame structure.

4. A magnetometer comprising a circular frame structure, a circular magnet having a gap therein, a calibrated scale, means supporting said circular magnet and said scale within said frame structure, said circular magnet having its ends :terminating in aligned spaced relation at the gap therein, a U-shaped frame mounted between the spaced ends of said magnet, an armature journalled in said U-shaped frame centrallyl of said circular` frame structure, said armature havingv .sets of arms extending in diametrically opposite directions normal to each other, an indicator carried by one of said. arms and coacting with said scale, permanent magnets carried by others of said arms and coacting with the circular mag- .net Within said frame structure, the ends of said arms being screw-threaded and adjustable weights engaged with the ends of each of said arms and adjustable toward or away fromv the journalled axis of said armature for counterbalancing said armature.

5. A magnetometer comprising a circular frame structure, a circular magnet having a gap therein,l a calibrated scale, means supporting said circular magnet and said scale within said frame structure, said circular magnet having its ends terminating in aligned spaced relation at thev gap therein, a U-shaped frame-mounted betweenthe spaced ends of said magnet, an armature journalled in said U-shaped frame centrally of said circular frame structure, said armature having sets of arms extending in diametrically opposite directions normal to each other, anA indicator carried by one of said arms and coacting with said scale, permanent magnets carried byv others :of said arms and coacting with theV circular mag;-

net within said frame structure, sleeve members extending from said framestructure in diametrically opposite directions and magnetic members insertable into and. removable from said sleeve members.

6. In a magnetometer, a frame structure, an

armature journalled with respect to saidframe structure, said armature being formed from magnetic material having sets of arms extending in diametrically opposite directions substantially normal to each other, one set of said arms having sockets formed therein, saidV last mentioned arms being screw-threaded at theirextremities, screwthreaded sleeve members engageable with the screw-threaded ends of said last-mentioned arms and permanent rod-likev magnetic members insertable into the sockets carried in said arms, the sleeve members on said last mentioned arms being adjustable with respect to said arms for distributing the mass of said armature with respect to the center of movement thereof.

7. In a magnetometer, a frame structure, an armature journalled with respect to said frame structure, said armature being formed from magnetic material having sets of arms extending in diametrically opposite directions substantially normal to each other, one set of said arms havingA sockets formed therein, saidlast mentioned arms being screw-threaded at their extremities, screwthreaded sleeve members engageable with, the screw-threaded ends of said last mentioned arms, permanent rod-like magnetic members insertable into the sockets carried in said arms, the sleeve members on said last' mentioned arms beingadjustable with respectto said arms for distributing the mass of said armature with respect to the center of movement thereof, an indicator carried by another of said arms and an adjustable sleeve associated with said last mentioned arm and movable concentrically with respect to said indicator toward or away from the center of movement of said armature.

8. In a magnetometer, a journalling means, an armature' mounted in said journalling means, radially extending magnetic projections on said armature, Screw-threads on the end of each of said projections, sleeve-like members internally screw-threaded to engage the screw-threads on the ends of said projections, one pair of said projections having sockets therein, permanent magnetic rods mountedin said sockets, another of said projections having a socket therein and an indicator mounted in the socket in said last mentioned projection.

9. In a magnetometer, a circular frame structure enclosing an annular calibrated scale therein, a curved magnetic member located within said frame structure and terminating in spaced ends, a supporting member extending into said frame structure between the spaced ends of said curved magnetic member, an armature journalled in said supporting member, said armature being formed substantially in the shape of a cross with magnetic projections extending in diametrical op- 10 posite directions, one pair of diametrically opposite projections having sockets in the ends thereof, magnetic rods supported in said sockets and the ends thereof movable in a path immediately adjacent said curved magnetic member and another of said projections having a socket therein for receiving an indicator movable with respect to said scale, the ends of said projections being externally screw-threaded and adjustable sleeves each internally screw-threaded and engageable over the external screw-threads on said projections for counter-balancing the operation of said armature.

FREDERICK W. LEE.

REFERENCES CITED The following references are of record in the le of this Ipatent:

UNITED STATES PATENTS Number Name Date 1,702,868 Hotchkiss et al. Feb. 19, 1929 1,909,619 Herrick May 16, 1933 2,123,045 Hoare July 5, 1938 2,151,627 Vacquier Mar. 21, 1939 2,357,319 Esval et a1. Sept. 5, 1944 2,397,137 Glennon et al Mar. 26, 1946 2,420,580 Antes May 13, 1947 2,487,047 Farnham Nov. 8, 1949 

